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Human Rights Watch on Saturday urged Iraqi authorities to give a government committee charged with probing a deadly raid by security forces on a protest camp last week greater financial and political backing to investigate who is responsible for what it described as an apparently unlawful use of lethal force.

The group also said it received photos from a separate, parliamentary investigation allegedly taken in the aftermath of the attack that showed the bodies of several men lying in the protest area amid burning cars. Some have their hands bound and "appear — because of the way the bodies are positioned — to have been executed with gunshots," the group said.

The April 23 crackdown on the Sunnis in Hawija who were protesting against the Shiite-led government unleashed a backlash of deadly attacks by Sunnis and battles between gunmen and security forces that have claimed more than 250 lives. The unrest poses the most serious threat to Iraq's stability since the last American troops left in December 2011, and raises fears of a new phase of widespread sectarian fighting.

Before the Hawija crackdown, local and tribal officials had been trying to negotiate a peaceful end to a standoff between protesters and security forces. Authorities had wanted to enter the camp to hunt for weapons and make arrests related to an earlier incident in which a nearby checkpoint came under attack.

Iraqi forces opened fire only after they were attacked, according to the Defense Ministry. It said 23 people, including three members of the security forces, were killed in the clashes. It said "only insurgents and extremists remained" in the camp before it moved in, and that some of the dead included militants with ties to al-Qaida and Saddam Hussein's outlawed Baath Party.

The Defense Ministry has said security forces opened fire only after they came under attack while trying to make arrests.

Hours after the raid, Prime Minister Nouri al-Maliki ordered the creation of a ministerial committee to investigate the incident. A parliamentary committee is also probing what happened at Hawija.

Human Rights Watch obtained a preliminary copy of the parliamentary investigation's findings. It said the committee determined that the crackdown by security forces on the Hawija camp killed at least 44 civilians. All were killed by live fire, and at least one of the dead was 13 years old, Human Rights Watch said.

The committee's casualty figures are similar to ones provided by Deputy Prime Minister Saleh al-Mutlaq, who leads the separate ministerial committee that is also investigating the Hawija incident. His office said 46 people not on the side of security forces, including minors, were killed.

Al-Mutlaq's committee has based its findings primarily on interviews with government officials and on photographs from the scene. He acknowledged difficulties in speaking to witnesses among the protesters because they are afraid to participate in the process.

"The problem is that we are only listening to one side," al-Mutlaq said in an interview with The Associated Press in an interview Wednesday.

Human Rights Watch believes al-Mutlaq's committee needs greater financial and political support. It said that the ministerial committee's failure to interview witnesses or participants in the crackdown raises serious doubts about the government's intention to hold those involved responsible.

The parliamentary committee inquiry, meanwhile, is based in part on interviews with witnesses who were at the protest. It did not talk to soldiers who were at the scene because it claims it was prevented from doing so by their superior officers, according to Human Rights Watch.

The parliamentary committee report "indicates that senior officials gave orders for army, federal police, and SWAT forces, all of which fall under Maliki's military office, to invade the demonstration site, remove demonstrators and level tents," the rights group said.

While it alleges that senior officials, including al-Maliki, may have ordered the raid, "it does not address what orders they issued concerning the use of force," according to the group.

Al-Maliki's spokesman, Ali al-Moussawi, denied that any orders were given to fire on protesters.

"There is no need to ask who issued the orders, because those orders did not exist in the first place," he said. As evidence, he said security forces nearest the protesters were armed only with water cannons and batons.

Members of the parliamentary committee could not immediately be reached for comment. Shiite lawmaker Hakim al-Zamili said the ad hoc committee originally included both Sunni and Shiite lawmakers, but the Shiites withdrew because they felt the members were jumping to conclusions prematurely and laying blame only on the government. He predicted that the sectarian makeup of the panel now would likely overshadow its findings.

Al-Mutlaq, who leads the separate ministerial committee, said he believes security forces used excessive force at Hawija. Western diplomats in Baghdad have also cited concerns about the large number of people killed among the protesters and the thoroughness of the ministerial investigation into the incident.

Al-Mutlaq has in the past clashed with al-Maliki, whose Shiite-led administration has been the target of more than four months of anti-government demonstrations led by the country's Sunni Arab minority. But unlike several other senior Sunnis, he continues to serve in the government, and he was chosen by al-Maliki to lead the probe into the Hawija incident.

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Associated Press writer Sameer N. Yacoub contributed reporting.

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